Implement a collapsible sidebar that can be folded to show just project
icons in a slim strip, or expanded to show full project details. Projects
can now have custom icons selected from a 6x6 grid of 36 symbolic icons.
Features:
- Foldable sidebar with toggle button (fold/unfold)
- Slim sidebar view showing only project icons when folded
- Custom project icons with 36 symbolic icon choices
- Icon picker dialog with 6x6 grid layout
- Edit Project dialog (renamed from Rename) with name and icon selection
- Project icons displayed in both full and slim sidebar views
- Smooth transitions between folded/unfolded states
- Click on slim project icon to unfold sidebar
Technical changes:
- Add icon field to Project model with default "folder-symbolic"
- Create constants.py with PROJECT_ICONS list (36 symbolic icons)
- Implement IconPickerDialog with grid layout and selection
- Create SlimProjectItem widget for folded sidebar view
- Update ProjectManager.update_project() to handle icon changes
- Restructure sidebar using GtkStack for full/slim view switching
- Update project-item.ui to display project icon
- Change "Rename" menu to "Edit Project" with icon picker
- Add fold/unfold buttons with sidebar-show icons
- Update build system with new files and resources
